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West Pacific/2015/09W/Archive/7
Public advisory TROPICAL STORM CHAN-HOM PUBLIC ADVISORY NUMBER 7 WIKI-HURRICANES FORECASTING CENTER 12:00 AM JST THU JUL 02 2015 ...CHAN-HOM STRENGTHENING... SUMMARY OF 12:00 AM JST...15:00 UTC...INFORMATION ------------------------------------------------------------------- LOCATION...10.9N, 155.2E CENTER POSITION CONFIDENCE: LOW ... ± 50 MI... 80 KM ABOUT 340 MI...550KM NW OF PALIKIR, MICRONESIA MAXIMUM SUSTAINED WINDS...45 KT...50 MPH...80 KM/H MINIMUM BAROMETRIC PRESSURE...997 MB...29.44 INCHES PRESENT MOVEMENT...W AT 17 KT...20 MPH...31 KM/H DISCUSSION AND 48-HOUR OUTLOOK --------------------------------------------- At 12:00 am JST, the center of Tropical Storm Chan-Hom was situated near 10.9N, 155.2E, or about 340 miles (550 kilometers) northwest of Palikir, Micronesia. Maximum sustained winds were 45 knots (50 mph, 80 km/h), with higher gusts. The minimum barometric pressure was 997 millibars (hPa; 29.44 inHg), and the cyclone was tracking west at 17 knots (20 mph, 31 km/h). The marginally favorable environmental conditions that Chan-hom is in will improve as the cyclone tracks further westward, which should allow for steady strengthening as it tracks generally west or west-northwestward. NEXT ADVISORY ------------------- Next complete advisory at 06:00 am JST. $$ Forecaster TheAustinMan Discussion TROPICAL STORM CHAN-HOM PUBLIC ADVISORY NUMBER 7 WIKI-HURRICANES FORECASTING CENTER 12:00 AM JST THU JUL 02 2015 Chan-hom's convective pattern has significantly improved over the last few hours. This largely is the result of the MLC-associated convection from yesterday fading away and being overtaken by LLC-associated convection that began developing during the evening hours and into nightfall. This change of circulation dominance has led to Chan-hom become more consolidated and more concentrated about the actually low-level circulation, and some cloud tops with temperatures at or colder than -100C have returned. Chan-hom appears to be developing banding features to its northwest, and cirrus indicative of good outflow is still evident. The center of circulation has been difficult to locate for much of the night, though the position can be narrowed down to some degree thanks to some microwave passes that occurred past dusk; consequently,it appears that the circulation has moved under cloud cover but is still displaced from the deepest convection Current satellite intensity estimates include 51kt from CIMSS-ADT and TX.X/XXkt from SAB. The intensity for this advisory has been set to 45kt. Despite the convective improvements, Chan-hom remains in a somewhat sheared environment, with wind shear analyzed by CIMSS to be around 10-20 knots, which has acted as a suppresant to any marked intensification despite the warm sea surface temperatures and oceanic heat content. Models are generally in agreement with the intensity forecast over the next 2-3 days as they generally anticipate steady strengthening due to the presence of some light wind shear and interaction with a developing area of low pressure to the southwest. In the tau 96 to tau 120 range, conditions are expected to become even more favorable west of the Mariana Islands, and several models, including the HWRF, GFS, and IFS, increase Chan-hom's pace of intensification during that time. This is largely in alignment with the WHFC forecasting philosophy for this system, and thus the intensity forecast has largely been maintained since the last advisory. The only marked inhibiting factor in that timeframe appears to be the potential for some dry air entrainment due to a passing upper-level low to the north, but this does not appear to be significant enough to warrant much change of the intensity forecast. Chan-hom has accelerated westward, which has largely been a byproduct of lessening shear allowing the low level center of circulation to gravitate towards the convective mass that had previously been well west of the center. Chan-hom's motion over the next two days will largely continue to be westward as a result of a strong subtropical ridge to its north. Chan-hom is expected to interact with a developing area of low pressure to the southwest today, and will likely end with the developing system merging with Chan-hom. This interaction should tug Chan-hom slightly southwest, which models have been indicating. An upper-level trough is expected to erode the western periphery of the subtropical ridge, forcing Chan-hom towards the northwest. The WHFC forecast track has remained largely unchanged as these parameters have mostly remained constant. This path will take it into the southern Mariana Islands, and interests in the area should closley monitor this system. INIT 01/1500Z 10.9N 155.2E 45 KT 50 MPH 12H 02/0000Z 11.2N 153.1E 50 KT 60 MPH 24H 02/1200Z 11.2N 150.6E 55 KT 65 MPH 36H 03/0000Z 11.6N 148.1E 65 KT 75 MPH 48H 03/1200Z 12.5N 145.8E 75 KT 85 MPH 72H 04/1200Z 14.0N 144.7E 85 KT 100 MPH 96H 05/1200Z 16.4N 143.1E 95 KT 110 MPH 120H 06/1200Z 19.0N 140.0E 110 KT 125 MPH $$ Forecaster TheAustinMan